I suppose your 371 EP application is the regional European patent application after the international phase, generally referred to as the Euro-PCT.
It is not allowed to include any prior applications by reference in said application (you may include the wording, but it will ahve no legal effect and probably you will need to remove it from the application upon grant).
Further, you may file the application with a new set of claims, but these claims (as for any other amenments that are later made to the claims) should be based on the application as filed, i.e. the PCT application. Please also be warned that 'based' in this sentence means that any amendedment should be clearly and unambiguously derivable from the application as filed. This is a very strict requirement under the European patent law and it has cost may US-based application the possibility to obtain a patent.
As a consequence, it is thus not possible to derive the amendment from the priority application if there is not a sufficient basis in the PCT application.